Trowel



Nov. 7, 1939. G'. .1. SHAFFER 2178.899

TROWEL Filed Feb. 5, 1939 Patented Nov. 7, 1939 UNITED STATES PATENTomer.

TROWEL Guy J. Shaffer, Palo Alto, Calif. Application February 8, 1939,serial No. 254,415 5f claims. (o1. 758-188) The present inventionrelates particularly' to that type of trowels used yin the applicationof plastic compounds to wall surfaces, and more particularly to a formof trowel for use in the application of a plastic compound to the jointsof a specific form of wall structure known as sheetrock.

In preparing such a wall for papering, or for any other desired type ofwall finish, it is of course necessary that the wall surface be leftperfectly smooth, and the joints solid and substantial. To accomplishthe desired results it has heretofore been customary for the workman touse a single blade trowel, and by the exercise of the greatest care andskill apply a cementitious compound of measurable thickness over ajoint, tapering it laterally on both sides until it merges with thegeneral surface of the wall. In performing the Work in this manner,particularly over a joint between two angularly disposed wall surfaces,it is extremely diflicult to guide the trowel accurately along thejoint, and it is particularly dicult to work the edges of the compound'down to a point 'where they will merge smoothly with the underlyingwall. 'I'he result is that when a joint is covered in this manner a moreor less irregular, or wavy, corner is produced and when the compositionis dry and hard the edges must be sandpapered down smooth with the wall.This sandpapering process is the most objectionable feature because itresults in the formation of a very ne dust which is both obnoxious andinjurious to the workman, creating conditions which make the contractorloath to undertake such work.

It is the principal object of the present invention, therefore, toprovide a trowel so constructed and arranged that a compound can besmoothly and evenly applied in any desired thickness to a joint by aWorkman who is not particularly skilled in the art.

It is another object of the invention to provide a trowel of thecharacter indicated that will automatically hold true to the line of thejoint, and that will apply the compound in such a manner as to obviatethe necessity of extensive sandpapering of the edges.

Finally, it is an object of the invention to provide a tool of thecharacter indicated that may be readily adjusted for use on a flat wallor on any degree of angle therein, and one that will be economical tomanufacture, simple in form and construction, strong and durable, andhighly efficient in its practical application.

In the drawing:

Figure l is a perspective view of a trowel embodying my invention, apart being broken away.

Figure 2 is a detail section on line 2 2 of Figure 1.

Figure 3 is a perspective view of a portion of the device showing amethod of forming the 5 hinged joint between the two blades.

Figure 4 is an illustration showing the method of application of thetrowel to an angular surface.

In the particular embodiment of the invention 10 herein disclosed I showat I and 2 two identical vtrowel blades hinged together along theiradjacent longer edges as indicated at 3.

At 4 is shown a supporting plate for the blades, and the blades areswingably mounted on the l5 plate by means of straps 5 which encirclethe hinge pin 6.

The plate 4 is provided with an upstanding portion 'I at its forwardend, and the upper end of this portion 'I is provided with a rearwardex- 20 tension 8 upon which is mounted a handle 3. The handle 9 isdisposed to lie in parallel relation to the hinge 3.

In order to effect any desired angular relationship between the twoblades I and -2 I provide the 25 following mechanism- I provide abearing member I IJ on the top edge of portion 'I and form a slotv II insaid portion extending from member I0 down to a point adjacent the hinge3 and at right angles thereto. At the lower end of the slot I mount abearing member I2.

In the bearing membersl and I2, and extending the full length of slotII, is a screw I3 journaled in said bearing members as shown. The screwI3 may be rotated in either direction by 35 means of a wing-nut I4.

At I5 is shown a follower block threaded onto the screw I3 and engagingthe part I to prevent its rotation with the screw. At I6 and I 'I aretwo links pivotally connected to the follower I5 at I8 0' and I9respectively, and to the blades I and 2 at 20 and 2| respectively.

Since the links IB and I'I are angularly disposed between the followerI5 and the two blades I and 2 it follows that when the screw I3 is 45rotated and the block I5 caused to move longitudinally thereon the twoblades will be simultaneously and equally adjusted about the hinge 3.They may be adjusted to lie in the same plane, or in angular relation toeach other on 50 either side of said plane.

A guide member is mounted on the trowel, and this member comprises aplate 22 provided with an arm 23 which is pivotally mounted on plate 4as at 24. The arm 23 parallels the side of 55 plate 4, and the plate 22is offset at 25 to enter an opening 26 formed in plate 4. By this meansthe portion 25 of plate 22 is brought to lie in the plane of plate 4 andis movable through a slot 21 formed in the hinge 3.

To adjustably position the guide member I provide a link 28 pivotallyconnected thereto as at 29 at one end, the other end being pivotallyconnected to a follwer block 30 as at 3l. The follower block 3B isthreaded onto a screw32 which is in turn journaled in the plate portion1 as at 33 and lies in the plane of said portion 1, being positioned ina slot 34 in said portion 1. This block 30 engages the plate as at 35 toprevent rotation therein, and the screw is actuated by means of awing-nut 36.

While the uses and applications of the trowel are varied, one specicapplication thereof -is illustrated in Figure 4. Here the wall isindicated at 31, and since it is desired to have the 5 compositionapplied with a thickness indicated at 38 over the joint 39 the screw 32isoperated to advance the guide member 22 as shown and the screw I3 isactuated to set the blades land 2 in the positions shown. The guidemember now supports the center` of. the trowel, prevents springing ofthe blades, and enables the operator to accurately follow the joint.

The composition applied in the manner described is uniformly thickthroughout the whole length over the joint and tapers laterally to afeather edge that merges smoothly with the wall and requires nosandpapering.

Although a certain specic embodiment of the invention has beenillustrated and described, it,y

will be understood that various alterations in the details ofconstruction and mode of assembly may be made without departing from thescope of the invention as indicated in the appended claims. f

I claim:

1. A trowel comprising, a supporting plate provided with a handle, apair of trowel blades hingedly mounted on one edge of the plate alongadjacent paralleledges, a screw rotatably mounted on the plate and inthe plane thereof, a

follower block threaded on to the screw and engaging the plate, andlinks connecting the block and blades whereby rotation of the screw willeect equal adjustment of the blades.

2. A trowel comprising, a supporting plate provided with a handle, apair of trowel blades hngedly mounted on one edge of the plate alongadjacent parallel edges, and means for adjustably positioning the bladesabout the hinge, said hinge having a slot formed therein, a guide memberadjustably mounted upon the plate and passing through said slot,and-adjusting means for the guide member.

3. A trowel comprising, a supporting plate `provided with a handle, apair of trowel blades positioning the blades about the hinge, said hingehaving a slot formed therein, and said plate having an opening formedtherein communicating with the slot, a guide member disposed in theopening and projecting through the slot, and adjustable supporting meansfor the guide member.

4. A trowel comprising, a supporting plate provided with a handle, apair of trowel blades hingedly mounted on one edge of the plate alongadjacent parallel edges, and means for adjusting the blades about thehinge, said hinge having a slot formed therein, and said plate having anopening `formed therein communicating with the slot, a guide memberhaving a part disposed to lie in the plane of the supporting plate andin said opening and slidably engaging said slot and a part'offset tooverlie the side of the plate, and adjustable supporting means for saidguide member.

5. A `trowel comprising, a supporting plate provided with a handle, apair of trowel blades hingedly mounted on one edge of the plate alongparallel edges, and instrumentalities adjustably associated with theplate and connected to the blades to adjustably position the bladesabout the hinge.

' GUY J. SHAFFER.

